Q: Have you or any other astronaut ever seen UFOs from orbit? (Bekki Partis, Brisbane, Australia)​

Astronauts have not seen any evidence of alien life. Reports of unidentified flying objects (UFOs) in images returned from the shuttle or station have turned out to be ice crystals, drifting orbital debris, lightning flashes, or meteors streaking through the dark atmosphere below. So far, our search for extraterrestrial life—and other civilizations in space—has turned up no proof of alien civilizations.

A couple of astronauts, most famously Gordo Cooper and Ed Mitchell [both now deceased, sadly], have stated publicly that they believed UFOs are evidence of alien spacecraft. I disagree, and I’m aware of no contemporary astronauts who maintain they have seen such spacecraft. I didn’t spot any, and I looked out the windows of my shuttles for hundreds of hours while in orbit.

We still see unexplained phenomenon in the skies around our planet, yet a light in the sky (caused by some natural phenomenon) is a long way from evidence of a visit by a spaceship from another civilization. That said, over a thousand planets have been discovered around other stars and there are at least 100 billion stars in our Milky Way, so the odds are good that life, even intelligent life, exists elsewhere in our galaxy. I think we’re likely to find simple life forms in our own solar system, perhaps on Mars or on the moons of the giant planets.

As to alien civilizations, our understanding of physics tells us that it’s simply too hard to travel between the stars. Even if they could, would aliens want to travel to our rather unexceptional sun? If there are extraterrestrials out there, we’ll discover them by searching for alien microbes in likely abodes in our solar system, and by listening for radio or laser signals from distant civilizations.

About Tom Jones

Former astronaut Tom Jones is a scientist, author, and pilot. In more than eleven years with NASA, Tom flew on four space shuttle missions to Earth orbit. On his last flight, he led three spacewalks to install the centerpiece of the International Space Station, the American Destiny laboratory. He has spent 53 days working and living in space. See his full bio here.